#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>

int main()
{
	char arr[] = "aBcDeEfGhI";
	printf("%s\n", arr);
	size_t sz = sizeof(arr) / sizeof(arr[0]);
	int i = 0;
	for (i = 0; i < sz; i++)
	{
		if (islower(arr[i]))
		{
			arr[i]=toupper(arr[i]);
		}
		else
		{
			arr[i]=tolower(arr[i]);
		}
	}
	printf("%s\n", arr);
	return 0;
}